Have you ever wondered what causes double yolk eggs?

A double-yolk egg occurs when two egg yolks are released into a hen’s oviduct too close together, and are encased inside the same shell.  ‘Double yolkers’ occur naturally at a rate of about 1 in every 1,000 eggs, and are most common in younger hens, due to their change in hormones at the onset of lay.  Typically, once the hens settle into a routine laying pattern, the production of double yolk eggs will diminish.